The title of this blog is taken from the two cities at the heart of British and American Government.
Westminster (a city in its own right - distinct from London), has developed almost by accident. Once a low lying, marshy island bounded by the branches of the River Tyburn and the Thames - it was first a royal residence in the time of King Canute [Some say that it was at Westminster that the King's inability to order back the tide was proved]. Edward the Confessor build a more extensive palace in order to be close to his pet project - the building of Westminster Abbey. Kings moved out in 1512 after a fire, and during the sixteenth century it finally established itself as the permanent seat of Parliament. The Fire of 1834 almost completely destroyed the old palace (Westminster Hall was saved - under the personal direction of the Prime Minister) and the opportunity arose for a new legislative building to be built almost from scratch. The surrounding area is now impressive and well kept - but prior to the fire was a crowded, unplanned mess.
The site of Washington of course was specifically chosen as the federal capital. There are some interesting books around about the building of this (relatively) planned city. I hugely enjoyed Nicholas Mann's "The Sacred Geometry of Washington, D.C. " (2006) - which has some interesting theories and leaves you with a much better idea of how the city is structured. My current bedtime reading is "The Washington Community 1800-1828" by James Sterling Young. It was published in 1966 and gives insights into both the geography of the city and the dynamics within the different communities who first lived in Washington. At one stage there were very distinct 'legislative' and 'executive' communities.